As the volume of digital data sent over communication lines rapidly grows, there is a continuous need for high bandwidth communication links. One specific need is for a method for simplifying multiplexing of 8b/10b encoded gigabit Ethernet data while maintaining the 8b/10b encoded spectrum having a higher low-frequency cutoff compared to time multiplexed signals.
Presently, statistical multiplexing on a packet-by-packet basis multiplexes lower-rate channels in a local area network (“LAN”) environment. For example, in LAN switches, Ethernet frames are multiplexed onto a higher-speed port frame-by-frame. Although the framing structure is usually preserved, Ethernet frames of different rate (e.g., 10/100/1000 Mb/s) have different encoding standards, requiring decoding and coding before and after multiplexing.
Other multiplexing techniques are possible that do not require a new standard because they involve combining or “trunking” of multiple links to a link of higher aggregate capacity. One example is “Etherchannel” that uses multiple pairs of wires or fibers that behave like a single data link of higher capacity. A different multiplexing scheme that is more efficient in its use of wiring is the wavelength-division-multiplexing (“WDM”) of individual data links onto a single optical fiber using different wavelengths. Similarly, time-division-multiplexing (“TDM”) is currently only used when many lower-speed (e.g., 10BASE-T) signals need to be sent over longer distances over a single fiber connection.
The aforementioned multiplexing techniques have significant disadvantages. Specifically, statistical packet multiplexing requires a definition of a new physical (i.e., the PHY-layer) and data-link (i.e., the MAC-layer) standard every time a LAN standard of higher speed is required. This standardization process can take years. It also requires buffers at least a few packets deep. Channel trunking or link aggregation is very wasteful with respect to wiring. WDM multiplexing is expensive over distances that do not require optical amplifiers because of the high cost of WDM optical components.
Based on the foregoing, there is a need for an improved method for high-speed transmission of data by multiplexing 8b/10b encoded gigabit Ethernet data while nearly maintaining the 8b/10b encoded spectrum.